cable stop strength

Francesco Devittori said:

Hi all,

I just repaired the rear derailleur cable stop that broke off from my
carbon fiber chainstay, but I don't know if it will hold in the long
run.

Is there a standard way to test this? How do frame builders do it?

Thanks,
Francesco

How was it originally attached? How did it become detached? Was there
any damage to the chainstay? How did you re-attach it?

To better serve you,

D'ohBoy

D'ohBoy said:

Francesco Devittori said:

Hi all,

I just repaired the rear derailleur cable stop that broke off from my
carbon fiber chainstay, but I don't know if it will hold in the long
run.

Is there a standard way to test this? How do frame builders do it?

Thanks,
Francesco

How was it originally attached? How did it become detached? Was there
any damage to the chainstay? How did you re-attach it?

To better serve you,

D'ohBoy

The cable stop is a square alu thing. It was fixed with a little screw
and very little glue (the bike is a first-generation C40).
I was able to drill out the broken screw, then attach the stop with a
similar screw and a good amount of bi-component epoxy glue (called
Araldit, I don't know if it's a known brand -it is here).
I guess the glue is what keeps things together, I don't think the screw
alone is strong enough to keep the cable stop in place under force.

A good thing is that the contact surface is relatively large and the
shape of the cable stop is a bit rounded and matches the chainstay.
Before gluing I roughed both surfaces with sandpaper and cleaned them
well.
It's now sitting for 24 hours, but already after a couple of hours I
was not able to move the cable stop with all the force of my hand.

What I'm most concerned is the long term durability (also cold
conditions/etc).
I don't want that it detaches in the middle of a race...

Francesco Devittori said:

D'ohBoy said:

Francesco Devittori said:

Hi all,

I just repaired the rear derailleur cable stop that broke off from my
carbon fiber chainstay, but I don't know if it will hold in the long
run.

Is there a standard way to test this? How do frame builders do it?

Thanks,
Francesco

How was it originally attached? How did it become detached? Was there
any damage to the chainstay? How did you re-attach it?

To better serve you,

D'ohBoy

The cable stop is a square alu thing. It was fixed with a little screw
and very little glue (the bike is a first-generation C40).
I was able to drill out the broken screw, then attach the stop with a
similar screw and a good amount of bi-component epoxy glue (called
Araldit, I don't know if it's a known brand -it is here).
I guess the glue is what keeps things together, I don't think the screw
alone is strong enough to keep the cable stop in place under force.

A good thing is that the contact surface is relatively large and the
shape of the cable stop is a bit rounded and matches the chainstay.
Before gluing I roughed both surfaces with sandpaper and cleaned them
well.
It's now sitting for 24 hours, but already after a couple of hours I
was not able to move the cable stop with all the force of my hand.

What I'm most concerned is the long term durability (also cold
conditions/etc).
I don't want that it detaches in the middle of a race...

should be stronger than the original. unless you have derailleur
problems that cause significantly excess tension, it should be fine.

jim beam said:

Francesco Devittori said:

[...]
I was able to drill out the broken screw, then attach the stop with a
similar screw and a good amount of bi-component epoxy glue (called
Araldit, I don't know if it's a known brand -it is here).
[...]

should be stronger than the original. unless you have derailleur
problems that cause significantly excess tension, it should be fine.

Thanks! This gives me some peace of mind.
I can now sleep better :-)

Francesco

On 10 Dec 2006 08:28:41 -0800, "Francesco Devittori"

may have said:

D'ohBoy said:

Francesco Devittori said:

Hi all,

I just repaired the rear derailleur cable stop that broke off from my
carbon fiber chainstay, but I don't know if it will hold in the long
run.

Is there a standard way to test this? How do frame builders do it?

Thanks,
Francesco

How was it originally attached? How did it become detached? Was there
any damage to the chainstay? How did you re-attach it?

To better serve you,

D'ohBoy

The cable stop is a square alu thing. It was fixed with a little screw
and very little glue (the bike is a first-generation C40).
I was able to drill out the broken screw, then attach the stop with a
similar screw and a good amount of bi-component epoxy glue (called
Araldit, I don't know if it's a known brand -it is here).
I guess the glue is what keeps things together, I don't think the screw
alone is strong enough to keep the cable stop in place under force.

A good thing is that the contact surface is relatively large and the
shape of the cable stop is a bit rounded and matches the chainstay.
Before gluing I roughed both surfaces with sandpaper and cleaned them
well.
It's now sitting for 24 hours, but already after a couple of hours I
was not able to move the cable stop with all the force of my hand.

What I'm most concerned is the long term durability (also cold
conditions/etc).
I don't want that it detaches in the middle of a race...

I'd say it should be good for a couple of years at least, as long as
the aluminum's surface was not contaminated with anything that would
eventually degrade the bond. There's a good chance that it'll last a
long as the chainstay.

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